Below you can find a YouTube video where Åkesson is using the instrument to murder a Scott Joplin ragtime song. While we admire his engineering skills, we lived long enough in Bulgaria to hate all forms of accordian. So the fact that Åkesson is an accomplished accordion player makes little difference.
He plays a melody with his right hand on one C64 keyboard and controls the chord of a rhythm and bass line loop (that he can pre-record using the flip of a switch) using his left hand on the other keyboard.
What is more interesting is the amount of custom software engineering that went into making the Commodordion. It builds off of earlier projects such as the Sixtyforgan (a C64 with spring reverb and a chromatic accordion key layout) and Qwertuoso, a program that allows live playing of the C64's famous SID sound chip.
Åkesson wired up a custom power supply, and when he flips the unit on, both Commodore 64 machines boot (no display necessary). Next, he loads custom music software he wrote from a Commodore Datasette emulator board into each machine.
A custom mixer circuit board brings together the audio signals from the two units and measures input from the bellows to control the volume level of the sound output. The bellows, composed of many 5.25-inch floppy disks cut and taped into shape, emit air through a hole when squeezed. A microphone mounted just outside that hole translates the noise it hears into an audio envelope that manipulates the sound output to match. The Commodordion itself does not have speakers but instead outputs its electronic audio through a jack.
It is uncomfortable to play because the unit puts strain on player's left wrist, arm, and shoulder due to the position of the keys on the left-hand side of the instrument—and the fact that his left arm also needs to bear the weight of the unit. "This rather undermines the potential for the Commodordion as a viable musical instrument," he writes.